The sharp increase in demand in lubricating oils and the limited petroleum reserves throughout the world have caused a sharp increase in the price of petroleum products and have led to great concern that the limited supplies will not meet future demand given the sharp increase in the demand from developing and developed countries. In recent years, large developing nations have become more industrialized and this has resulted in the demand for petroleum products in these countries rising significantly. In addition, each year large amounts (e.g., 150 million barrels or more) of used lubricating oils, such as automotive oils, gear oils, turbine oils, and hydraulic oils which through usage or handling are unfit for their intended use, are generated world-wide. Used oil that is derived from 150 million cars or more and other machines accumulates in thousands of service stations, repair shops and industrial plants.
Lubricating oil does not wear out during use but over time it does become contaminated with heavy metals, water, fuel, carbon particles and degraded additives. Eventually, the lubricating oil becomes so contaminated that it cannot satisfactorily perform its lubricating function and therefore must be replaced. Public opinion and government intervention and new legislation are increasingly demanding the material recycling, rather than the burning or dumping, of waste products. Used lubricating oil can contain 60 to 97% highly valuable materials (which is generally in the form of mineral oil and synthetic oil fraction) which is worth significantly more than heavy fuel oil. It is therefore desirable to extract and reuse the valuable materials.
Besides being illegally dumped, used lubricating oils can be treated in a number of different ways including but not limited to: (1) burning the lubricating oils as fuel after stripping sludge and water therefrom; (2) direct burning of the lubricating oil; and (3) re-refining the spent lubricant oils into base stocks. When used oil is either burned directly or as fuel after stripping treatment, the contaminants in oil are emitted as atmospheric pollutants. This also results in wasting base oils which otherwise could be recovered and reused.
Accordingly, re-refining is needed to collect lubricating oil and to re-refine used oil into quality material to reduce consumption of virgin base oils and, thereby conserving energy and natural resources. Unfortunately, to date, refiners of crude oil have not aggressively implemented and undertaken the recovery of base oils. This is because, in part, although used oil represents a sizable raw material source for re-refining, its volume is relatively small compared to the world's crude oil market. In addition, used oil is contaminated with added substances and impurities which can cause expensive disruption and downtime in conventional refining facilities.
It has been known since the early 1900s that used lubricating oil from engines and machinery can be recycled. However, despite a number of different re-refining techniques being implemented over the years to extract base oils from lubricants, most of these techniques (1) have low product yields; (2) do not solve potential pollution; (3) produce base oils with poorer quality than virgin base oils; and (4) are costly to implement.